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12 Cards in this Set
- Front
- Back
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How is the structure of the villus related to its role in absorption and transport of the products of digestion?
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1. villus – large surface area ((due to folding of the tissue) to increase efficiency of absorption of (soluble) food and to create increased surface area for digestion (e.g. disaccharides) 2. lacteal / lymphatic duct/vessel present – transport of fat/lipid that are absorbed at the villus; 3. Circular muscles and longitudinal muscles—antagonistic muscles that move food through the small intestine 4. Epithelial cells of villus—absorption of nutrients (more detail in future) 5. Goblet cells of villus (near base)—secrete mucus
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Identify #12 in the picture of the transverse section of the ileum.
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lacteal
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Identify #13 in the picture of the transverse section of the ileum.
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villus
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Identify #14 in the picture of the transverse section of the ileum.
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circular muscles
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Identify #15 in the picture of the transverse section of the ileum.
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longitudinal muscles
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What 5 materials are not absorbed and are egested by the digestive system?
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cellulose, ligning, bile pigments, bacteria, intestinal cells
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Identify #1 in the picture of the epithelial cell of a villus
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microvilli (singular: microvillus)
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Identify #2 in the picture of the epithelial cell of a villus
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tight junction
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Identify #3 in the picture of the epithelial cell of a villus
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pinocytotic vesicles
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Identify #4 in the picture of the epithelial cell of a villus
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mitochodria (singluar: mitochondrion)
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Explain how the structure of a villus is related to its function.
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Villi increase surface area for nutrient absorption; There is a single layer of epithelial cells on the villus, so the food molecules don’t have to travel too far to be absorbed; Microvilli on epithelial cells further increases surface area for absorption; Intrinsic protein channels in the epithelium cell for rapid facilitated diffusion of nutrients ; Pumps in the epithelium cells for active transport of nutrients; Pinocytotic vesicles (especially near microvilli)—formed in endocytosis for transport of nutrients into the cell; Distance between blood capillaries and epithelium cells is short so food molecules don’t have to diffuse very far. Capillaries carry glucose, amino acids, and other hydrophilic foods.; The lacteal (a branch of the lymphatic vessels) carries away lipids after absorption. The lipids then travel through the lymph system; Tight junctions firmly link epithelial cells to prevent molecules from leaking between the epithelial cells…by requiring food to pass through a membrane, absorp
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Explain the mechanisms used by the ileum to absorb and transport food.
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Active transport by epithelium cells—Protein pumps move glucose, amino acids, mineral ions (sodium, calcium, iron); Simple diffusion for lipids, fatty acids, glycerol; Endocytosis by epithelium cells—makes vesicles from plasma membrane. Allow bulk movement of fluid from ileum lumen to the inside of the cell, where the digested food can be absorbed from the vesicle into the cytoplasm
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